Here's Fidelity.

All Fidelity brokerage and mutual fund accounts are eligible for electronic funds transfer (EFT), with the exception of Self-Employed 401(k) plans, Self-Directed Brokerage accounts, SIMPLE IRAs, Fidelity Retirement plans (Keogh), and non-prototype accounts. Trust, business accounts, inherited IRAs, stand-alone SMA, and Fidelity personalized portfolio accounts must establish the EFT service by completing the Electronic Funds Transfer (EFT) Authorization (PDF). Inherited IRA accounts cannot accept contributions via EFT.

Are there other options for transferring money?
There are several other ways you can transfer money into or out of a Fidelity account, including through paper checks and third-party payment apps like PayPal and Venmo. Fidelity accounts are currently compatible2 with PayPal, Venmo, Square, Apple Pay, Google Pay, and Samsung Pay. For more information, see our mobile payments page.

To deposit a paper check into a Fidelity account, you can upload a photo of the check to the Fidelity Mobile App, or deposit it directly at a local Fidelity investor center. You can also withdraw money from your Fidelity account and have it sent via a paper check that’s mailed to you or another recipient. If you request to have a check sent to you or someone else, the check takes about 5 to 6 business days to process before it's mailed.